Karen Salazar soutiendra sa thèse intitulée : “Systematics Origin and diversification of the South American lady birdbeetle Eriopis (Coleoptera) elucidated by museomics," conduite sous la tutelle de l'unité de recherche ISYEB (UMR7205)
le vendredi 10 décembre à 9:30h.
La soutenance est publique et sera retransmise aussi à distance sur zoom:
ID de réunion : 846 6453 7448
Code secret : 087243
- Composition du jury :
Mr. Adam Ślipiński, professor, CSIRO, Canberra – Rapporteur
Mr. Emmanuel Toussaint, chercheur, Muséum d'Histoire naturelle, Genève – Rapporteur
Mme. Clio Der Sarkissian, chercheur, CR CNRS – Examinateur
Mme. Violaine Llaurens, chercheur, DR CNRS – Examinateur
Mr. Guillaume Achaz, professor, Musée de l'Homme, Collège de France – Directeur de thèse
Mr. Romain Nattier, MC, Muséum national d'Histoire naturelle, Paris – Co-encadrant de thèse
In South America, the uplift of the Andes Cordillera is a significant factor that altered the process of population divergence that ultimately led to speciation. Previous studies have shown contrasting results, where some Andean lineages have diversified early on during the Mio-Pliocene intense uplift period. In contrast, others diversified later in the Pleistocene, another postulated promoter of diversification during the glaciations in the Quaternary. The main objective of my thesis is to test the relative influence of the Mio-Pliocene intense uplift and the Pleistocene glacial cycles on the diversification of an insect group. I focused on the South American genus of ladybird beetles Eriopis (Coleoptera, Coccinellidae). This genus has 23 described species distributed on the Andean Mountains chain that spans from Venezuela to Patagonia and includes the Chilean Pacific Islands and South-East South America. Among the species that occur along the whole Andes cordillera, most are endemic and restricted to mountain ecosystems. Only a few live at low altitudes and have wider spatial distribution outside the Andes. For the broad distribution, Eriopis constitute a relevant group to test whether the climate changes and/or orogenesis have impacted the diversification rate of insect species. To test for the two competing hypotheses, I have reconstructed the evolutionary history of Eriopis based on the genomic data of specimens deposited in different Natural History Collections. The taxonomic revision based on the type specimens and several other specimens, supported by the morphological characters, supports that the diversity of this genus is larger than recognized before. I added new revalidations for four species and seven new ones. Thus, now 36 species could belong to Eriopis, placing this endemic genus as one of the most diverse among genera of the South American ladybird beetles. I used a high-throughput sequencing method and a broad sample of museum specimens aged 1 to 186 years before DNA extraction to perform the first species phylogeny of Eriopis. I recovered complete mitogenomes and several nuclear genes, even in the oldest samples. I performed a comparative analysis of the mitochondrial genome organization among the species. The Bayesian temporal calibration analysis indicates that this genus diverged in the middle of the Miocene around 16 Ma (Million years ago) or 9.0 Ma. After the middle of the Miocene, two significant clades separated from the main clade Miocene. The subsequent diversification of both clades was mainly after the last 3.0 Ma, and the most rapid diversification occurred the last 1.0 Ma. The biogeographic ancestral state reconstructions suggest that Central Andes was probably the center of origin of this group. Most of the lineages diverged in the highlands of the Central Andes, while others dispersed outside the continent to the Pacific islands. The colonization of the lowlands on both sides of the Andes occurred at least five times independently. The divergence estimates times suggest that the rise of Andes, especially the last uplift phases in Miocene, and the climatic fluctuations during Pliocene and Pleistocene were the main factors that tuned the diversification process of this genus.